發(fā)布時(shí)間：2018-05-04 09:14

  本文選題：封閉空腔 + 載荷識(shí)別��； 參考：《合肥工業(yè)大學(xué)》2014年博士論文

【摘要】：彈性封閉空腔結(jié)構(gòu)在動(dòng)態(tài)載荷激勵(lì)下產(chǎn)生振動(dòng)進(jìn)而形成的空間復(fù)雜聲場(chǎng)是工程實(shí)際中最具代表性的一類(lèi)聲場(chǎng)，如汽車(chē)、船舶和飛機(jī)的艙內(nèi)聲場(chǎng)。對(duì)該類(lèi)聲場(chǎng)的研究一直以來(lái)都是振動(dòng)與噪聲控制領(lǐng)域的一個(gè)重要研究方向，實(shí)現(xiàn)對(duì)這類(lèi)封閉空腔結(jié)構(gòu)內(nèi)部聲場(chǎng)的聲學(xué)響應(yīng)預(yù)測(cè)和分析，具有重要的理論研究意義和廣闊的工程應(yīng)用前景。 根據(jù)傳遞路徑分析方法的原理，系統(tǒng)響應(yīng)可認(rèn)為是外界激勵(lì)通過(guò)多種不同路徑傳遞到響應(yīng)點(diǎn)的能量貢獻(xiàn)疊加。因此通過(guò)識(shí)別外界激勵(lì)載荷和計(jì)算結(jié)構(gòu)振動(dòng)聲輻射來(lái)解決復(fù)雜封閉空腔結(jié)構(gòu)的振動(dòng)噪聲分析與控制問(wèn)題。 本文以封閉空腔結(jié)構(gòu)受激所形成的內(nèi)部復(fù)雜聲場(chǎng)為研究對(duì)象，用結(jié)構(gòu)部件的面板聲學(xué)貢獻(xiàn)度代替先前的傳遞路徑貢獻(xiàn)量，以預(yù)測(cè)和控制封閉結(jié)構(gòu)聲腔內(nèi)的聲學(xué)響應(yīng)為目標(biāo)，深入研究結(jié)構(gòu)外界激勵(lì)載荷的識(shí)別和復(fù)雜封閉空腔內(nèi)部聲場(chǎng)響應(yīng)計(jì)算兩個(gè)關(guān)鍵問(wèn)題。在激勵(lì)載荷的識(shí)別方面，提出了具有一般意義的結(jié)構(gòu)動(dòng)態(tài)載荷時(shí)域識(shí)別方法，提高了載荷識(shí)別的精度和穩(wěn)定性。在振動(dòng)聲輻射計(jì)算求解方面，提出了用于計(jì)算復(fù)雜封閉結(jié)構(gòu)振動(dòng)形成的內(nèi)部空間聲場(chǎng)的等效聲傳遞向量法，避免了邊界元法的固有缺點(diǎn)，計(jì)算效率更高。在封閉空腔結(jié)構(gòu)內(nèi)聲場(chǎng)預(yù)測(cè)和聲學(xué)優(yōu)化方面，提出了一種基于等效源法的內(nèi)部近場(chǎng)聲全息的面板聲學(xué)貢獻(xiàn)度計(jì)算方法，該方法可在重建封閉空腔結(jié)構(gòu)內(nèi)聲場(chǎng)的同時(shí)，有效識(shí)別出各振動(dòng)板件對(duì)封閉聲場(chǎng)的聲學(xué)貢獻(xiàn)度。完成的主要研究工作和成果如下： （1）闡述了封閉空腔結(jié)構(gòu)內(nèi)部聲場(chǎng)分析的研究意義，詳細(xì)回顧了動(dòng)態(tài)載荷識(shí)別方法和封閉空腔結(jié)構(gòu)內(nèi)部聲場(chǎng)計(jì)算的研究現(xiàn)狀和進(jìn)展，分析了其中仍然存在的一些值得研究的問(wèn)題，并以此為基礎(chǔ)，確定了本論文所要研究的主要內(nèi)容。 （2）針對(duì)響應(yīng)中帶有噪音時(shí)載荷識(shí)別的困難，提出了聯(lián)合奇異熵去噪修正和正則化預(yù)優(yōu)的共軛梯度迭代識(shí)別方法。系統(tǒng)的振動(dòng)響應(yīng)表示為單位脈沖響應(yīng)函數(shù)與激勵(lì)載荷的卷積，并離散化一組線(xiàn)性方程組，將載荷識(shí)別問(wèn)題即轉(zhuǎn)化為求解線(xiàn)性方程組的反問(wèn)題。一方面對(duì)含噪信號(hào)進(jìn)行基于奇異熵的去噪處理，提高反問(wèn)題求解中輸入數(shù)據(jù)的精度。另一方面利用正則化方法對(duì)共軛梯度迭代算法進(jìn)行預(yù)優(yōu)，改善反問(wèn)題的非適定性。由于從輸入的響應(yīng)數(shù)據(jù)去噪和正則化算法兩方面同時(shí)改善動(dòng)態(tài)載荷識(shí)別反問(wèn)題的求解，因此可以有效地抑制噪聲，提高識(shí)別精度。通過(guò)數(shù)值算例分析，，表明在不同的噪聲水平干擾下，其識(shí)別精度均優(yōu)于常規(guī)的正則化方法，能夠?qū)崿F(xiàn)有效穩(wěn)定地識(shí)別動(dòng)態(tài)載荷。最后通過(guò)實(shí)驗(yàn)研究進(jìn)一步驗(yàn)證了該方法的正確性和有效性。 （3）對(duì)封閉空腔結(jié)構(gòu)內(nèi)聲場(chǎng)分析計(jì)算問(wèn)題的數(shù)值求解方法進(jìn)行了詳細(xì)的論述，推導(dǎo)了求解Helmholtz方程的聲學(xué)有限元法和聲學(xué)邊界元方法的理論公式，并分析了這兩種數(shù)值計(jì)算方法在實(shí)際應(yīng)用中的不足之處。 （4）推導(dǎo)了基于邊界元法的聲傳遞向量的計(jì)算公式。提出了用于分析復(fù)雜封閉空腔結(jié)構(gòu)內(nèi)聲場(chǎng)的等效聲傳遞向量法，導(dǎo)出了等效聲傳遞向量和面板聲學(xué)貢獻(xiàn)度的理論公式，研究了等效聲傳遞向量法的數(shù)值計(jì)算誤差影響因素。該方法避免了邊界元法中復(fù)雜的數(shù)值計(jì)算和奇異積分的處理過(guò)程，簡(jiǎn)化了計(jì)算過(guò)程，有利于向工程實(shí)際推廣。分別以三個(gè)不同形狀結(jié)構(gòu)形成的聲腔模型為例進(jìn)行聲場(chǎng)分析，仿真實(shí)驗(yàn)結(jié)果證明了該方法的正確性和有效性。 （5）基于等效源法的內(nèi)部聲全息技術(shù)，提出了一種復(fù)雜封閉空腔結(jié)構(gòu)內(nèi)聲場(chǎng)的面板聲學(xué)貢獻(xiàn)度識(shí)別方法。首先重構(gòu)出振動(dòng)結(jié)構(gòu)表面的法向振速，實(shí)現(xiàn)對(duì)整個(gè)內(nèi)部封閉聲場(chǎng)的預(yù)測(cè)，再將振動(dòng)結(jié)構(gòu)的每個(gè)面板在腔體內(nèi)部場(chǎng)點(diǎn)產(chǎn)生的聲壓分別用位于空腔表面附近的等效源在該點(diǎn)產(chǎn)生的輻射聲壓代替，將復(fù)雜的封閉非自由聲場(chǎng)問(wèn)題轉(zhuǎn)化為簡(jiǎn)單的內(nèi)部自由場(chǎng)問(wèn)題，結(jié)合重建出的結(jié)構(gòu)表面法向振速進(jìn)而識(shí)別出封閉振動(dòng)結(jié)構(gòu)各面板對(duì)腔體內(nèi)任意位置的聲學(xué)貢獻(xiàn)度。研究了等效源的數(shù)量及與重建面距離等參數(shù)對(duì)重建精度的影響，通過(guò)復(fù)雜結(jié)構(gòu)內(nèi)聲場(chǎng)的數(shù)值仿真和實(shí)驗(yàn)研究的結(jié)果驗(yàn)證了所提方法的正確性和有效性。 （6）總結(jié)本文的主要研究成果，指出了需要進(jìn)一步研究和解決的問(wèn)題。
[Abstract]:The space complex sound field formed by the vibration of the elastic closed cavity structure under the dynamic load excitation is the most representative sound field in the engineering practice, such as the acoustic field in the vehicle, the ship and the aircraft. The prediction and analysis of acoustic response inside the closed cavity structure has important theoretical significance and broad engineering application prospects.
According to the principle of the transfer path analysis, the response of the system can be regarded as the superposition of the energy contribution of the external excitation through a variety of different paths to the response point. Therefore, the vibration noise analysis and control of the complex closed cavity structure can be solved by identifying the external excitation load and calculating the structural vibration sound radiation.
In this paper, the internal complex sound field formed by the excitation of a closed cavity structure is taken as the research object. The acoustic contribution of the panel's panel is replaced by the contribution of the previous transmission path, and the acoustic response in the closed structure sound cavity is predicted and controlled as the target. The recognition of the external excitation load and the internal sound field in the complex closed cavity are deeply studied. In response to two key problems, the time domain identification method of structural dynamic load with general significance is proposed to improve the accuracy and stability of load identification. The equivalent sound transfer of internal space sound field for calculating the vibration formation of complex closed structures is proposed in the calculation of vibration acoustic radiation. The vector method avoids the inherent shortcomings of the boundary element method and has a higher calculation efficiency. In the aspect of acoustic field prediction and acoustic optimization in the closed cavity structure, a method for calculating the acoustic contribution of the panel based on the equivalent source method is proposed. This method can effectively identify the sound field in the closed cavity structure and effectively identify the vibration. The main contributions of the research work are as follows:
(1) the research significance of the internal sound field analysis of the closed cavity structure is expounded. The research status and progress of the dynamic load identification method and the internal sound field calculation of the closed cavity structure are reviewed in detail, and some problems that still exist in the cavity structure are analyzed, and the main contents of the study are determined on the basis of this.
(2) in response to the difficulty of load recognition in response to noise, a conjugate gradient iterative identification method with combined singular entropy de-noising correction and regularization predominance is proposed. The vibration response of the system is expressed as a convolution of the unit impulse response function and the excitation load, and a set of linear equations is discrete, and the problem of load identification is transformed into a solution line. The inverse problem of the sex equation group. On the one hand, the noise signal is denoised based on the singular entropy to improve the accuracy of the input data in the inverse problem solving. On the other hand, the regularization method is used to predominate the conjugate gradient iterative algorithm and improve the inadaptability of the inverse problem. Two aspects of the denoising from the input response data and the regularization algorithm are made. At the same time, it improves the solution of the inverse problem of dynamic load identification, so it can effectively suppress the noise and improve the recognition accuracy. Through numerical example analysis, it shows that the recognition accuracy of different noise level interference is better than the regular regularization method, and it can realize the dynamic load effectively and steadily. Finally, the experimental research is further tested. This method is proved to be correct and effective.
(3) the numerical solution of the analysis and calculation of the acoustic field in a closed cavity structure is discussed in detail. The theoretical formulas for the acoustic finite element method and the acoustic boundary element method for solving the Helmholtz equation are derived, and the shortcomings of the two numerical calculation methods in practical application are analyzed.
(4) the calculation formula of sound transfer vector based on boundary element method is derived. An equivalent sound transfer vector method for analyzing the sound field in complex closed cavity structure is proposed. The theoretical formula of the equivalent sound transfer vector and the acoustic contribution degree of the panel are derived, and the influence factors of the numerical calculation error of the equivalent sound transfer vector method are studied. The method is avoided. In the boundary element method, the complex numerical calculation and the processing of the singular integral are simplified. The calculation process is simplified and it is beneficial to the engineering practice. The sound field analysis is taken as an example of three different shape structures. The simulation results prove the correctness and effectiveness of the method.
(5) based on the internal acoustic holography of the equivalent source method, a method to identify the acoustic contribution degree of the panel in a complex closed cavity structure is proposed. First, the normal velocity of the vibration structure is reconstructed to realize the prediction of the whole internal closed sound field and the sound pressure produced by each panel of the vibration structure in the interior of the cavity. By replacing the sound pressure generated by the equivalent source near the surface of the cavity, the complex closed non free sound field is converted into a simple internal free field problem. The acoustic contribution of the closed vibration structure to any position of the cavity in the cavity is identified by combining the reconstructed structure surface method to the velocity of vibration. The effect of the number of the source and the distance from the reconstruction surface on the reconstruction accuracy is verified by the numerical simulation and experimental results of the sound field in the complex structure.
(6) summarize the main research results of this paper, and point out the problems that need further research and solution.

【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TB535

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